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March 20

Cognitive bias for thinking everything a science field produces is positive?

Is there a term for folks in particular science fields who are so enmeshed in what they're doing that they develop a cognitive bias for being optimistic about everything contributed to the world from their field?

Take me, for example, as someone with a software engineering background, I frequently found myself thinking in terms of software being able to solve any problem. But as I've distanced myself from the field, it becomes clearer how unobjective I was in thinking like that.

Is Pro-innovation bias the best fit? I am asking a user of the Wikipedia rather than as an editor -- I don't intend to use any answer for editing purposes. Stevie is the man! ^{Talk • Work} 15:28, 20 March 2018 (UTC)

That is difficult because a priori its also a central nature of science to test and refute theories when they are wrong. There are early greek idealized philosophical theories about the reign of the wise, today collected in the term Noocracy and there is also Technocracy as a similar concept. Taylorism and Fordism are something similar too. These all imply the believe that pure science is the best of all ways to rule, judge and organize. However again, science includes questioning its ideas, altho it may take some time to conclude it was not good like Albert Einstein about his help to develop the nuclear bomb or Alfred Nobel inventing Dynamite. Science even recently "invented" Technology assessment as a new science! --Kharon (talk) 16:37, 20 March 2018 (UTC)

Thank you. That goes in the direction I intend, but I am trying to focus on a particular cognitive bias of the scientist (as an imperfect human being) in a specific field (which can be any specific field), whereas they become so idealized by their field that they in a sense become PR or evangelists for it. They ignore (or pretend to ignore) the negative ramifications of what their field produces, while seizing opportunities to trample on critics, no matter how well-founded the criticism. They make continual efforts to mold the minds of others toward their "positives only" view of their field. Maybe such scientists are indeed PR folks with a scientific background, but I don't want to assume they are PR. I wonder if there is a true cognitive bias here. Stevie is the man! ^{Talk • Work} 17:08, 20 March 2018 (UTC)

It also depends on what you mean by science. I would consider software engineering to be a branch of engineering. Engineers typically think they can solve the world's problems. And they can do it better than most other people too, but you might end up with something like China with them in charge. Or did you mean computer science? Scientists tend to be a bit more modest. Dmcq (talk) 18:28, 20 March 2018 (UTC)

I'd rather not say what specific field I'm thinking of, as I would like to avoid a debate about that field. But I will say that a field where science is applied fits into this model. So you could say I'm referring to a cognitive bias of a scientist or engineer. Stevie is the man! ^{Talk • Work} 18:50, 20 March 2018 (UTC)

Lots of biases could be used to describe this, but no one single phrase says it all. In-group_favoritism is relevant. As for the science/engineering thing Dmcq mentions, see[1], which specifically calls out Physicists as thinking they can do anything. On the other hand, I know plenty of Mechanical and Electrical engineers that don't think software is engineering. Anyway, I agree that many members of any group can get carried away overvaluing the contributions and abilities of that group. You can see it with computer folks, you see with with some academics. You can find fashion experts who will look you straight in the eye and say that fashion is all that matters. It's a little bit of in-group favoritism with sort of a group-level Dunning-Kruger effect. Which is not to say that everyone in these groups does it. I agree with Dmcq insofar as most of the very accomplished scientists I have met tend to be very cognizant of their field's limitations. As for the value of getting some distance from the field, that is also much discussed, though under many different terms (and in different fields). See e.g. Field_theory_(sociology), Standpoint_theory, Overview_effect, Cognitive_shift, this blog post [2] on the value of outsider's perspectives. SemanticMantis (talk) 18:46, 20 March 2018 (UTC)

There's scientism and technoutopianism. Sagittarian Milky Way (talk) 18:55, 20 March 2018 (UTC)

March 21

Big toe anatomy

I am looking for information of the anatomy of the big toe, but all the pictures and info I can find only show the big toe joint close to the foot, I am looking for info on the first big toe joint that bends close to the nail, what is it called? I am also wondering if this is an actual joint with cartilage or just bones.--User777123 (talk) 04:04, 21 March 2018 (UTC)

That joint has a synovial membrane. The end bone has a double concavity. The bone is called Pedal distal phalanx 1. The big toe has no middle phalanx. There are collateral ligaments on either side. It is connected to plantar ligament connected to articular capsule. Info from Cunningham's Text-Book of Anatomy, 9th ed, by James Couper Brash. A picture of the bone is here: http://www.eskeletons.org/boneviewer/nid/12537/region/feet/bone/pedal_distal_phalanx_1 . It connects to Extensor hallucis longus muscle. Graeme Bartlett (talk) 07:40, 21 March 2018 (UTC)

I'll add that the joint closest to the nail is called the interphalangeal joint of the hallux (aka digit 1 of the foot). -- Flyguy649 ^talk 22:13, 22 March 2018 (UTC)

Weighing scale

Can anyone please point me to a weighing scale which can measure mass up to 1 kg (or, if not, then at least up to 500 g), with the highest possible precision (if possible, ±10 mg or better, but if not, then the best available) and with the greatest possible accuracy? I bought one which meets these specs (or so I thought) on eBay, but it turned out to be a piece of junk -- just today I tried to weigh a 2 L beaker full of water, and it showed the weight as 1410 kg (and that right after calibration!), and as far as smaller weights (like empty beakers, or even a 1 L beaker half full of alumina powder), it remains stubbornly stuck at 0.00 g! 2601:646:8E01:7E0B:0:0:0:9ED6 (talk) 06:36, 21 March 2018 (UTC)

It appears that 2kg broke your 1kg limit scale. Anyway you want accuracy to 1 part in 100,000. You will have to take into account air buoyancy, which will vary at your precision with temperature and pressure. So you will need to weigh in a vacuum or have extra compensation. I can see examples that should be a good enough quality here: https://www.instrumentchoice.com.au/instrument-choice/other-meters/digital-scales-1/precision-and-analytical-balances and another here: http://www.scaleshop.com.au/adam-nimbus-nbl-e/ . Some of the scales here https://www.austscientific.com.au/product/balances/ have compensation for pressure and temperature (but I did not see humidity) and also prevent electric fields that also affect measurements. But they mostly do not meet your requirements for maximum. Graeme Bartlett (talk) 08:10, 21 March 2018 (UTC)

Actually, all 3 of them are good, but far too expensive -- I guess I'll have to settle for using 2 scales, one for weighing small amounts of chemicals (up to, say, 100 g) with high precision, and another one for weighing large amounts (up to 1 kg, preferably higher) with rather lower precision. 2601:646:8E01:7E0B:0:0:0:9ED6 (talk) 08:52, 21 March 2018 (UTC)

I'm slightly confused, did you scale support up to 1kg or did it supposedly support a higher weight limit? If it was only up to 1 kg and you tried to weigh something heavier like a 2L beaker full of water, it's not completely surprising it would break perhaps permanently as Graeme Bartlett has said. With the cheap scales I've bought from AliExpress I've generally gotten away with a fair amount of abuse. But if I was buying a expensive high precision scale from a proper manufacturer, I wouldn't be testing the limits especially to such an extreme. You can only go so far until you actually damage the strain gauge or whatever is used or something else. (In any case, for something from eBay particularly if it's new and from an uncertain manufacturer, you should always consider the possibility it may be DOA. So test it properly when it first arrives and report it to the seller if it is so you can get a replacement.)

Anyway I have seen ultra high precision, supposedly 1 mg scales, supporting up to 1 kg and with an enclosed measuring surface on AliExpress e.g. www.aliexpress .com/item/1kg-0-001g-1mg-electromagnetic-scale-calibration-weights/32810440445.html. And high precision, supposedly 10 mg, scales supporting up to 1kg are very common both the cheap dime a dozen ones which don't even have an enclosed measuring surface (so you know that at a minimum, the accuracy is very questionable) e.g. www.aliexpress .com/item/1PC-Professional-Pocket-1KG-0-01G-Scale-Digital-Jewelry-Precision-Balance-Weighing-Scale-With-Backlight-Keyboard/32819638592.html and those that do e.g. www.aliexpress .com/item/New-APTP457B-Precision-Jewelry-gold-food-weighing-counting-kitchen-scale-1KG-x-0-01g-Laboratory-analytical/32622805989.html.

I'm not suggesting you get these if you actually need these for an important reason (I do actually use a 0.01g scale from AliExpress/eBay but only really for fun, e.g. cooking, in fact 0.1g would do I mostly want something more than 1g and it's a choice between 3kg or so 0.1g and 1kg or so and 0.01g). But these suggest to me you should be able to get one from a decent manufacturer. As GB has said, if you actually need that level of precision you'll need to consider carefully compensation measures.

Nil Einne (talk) 08:36, 21 March 2018 (UTC)

For the record, the scale I have is rated to measure weights up to 3 kg (in fact, the calibration weights are 2 kg in all) -- therefore, my weighing the beaker could not possibly have anything to do with the malfunction (and in any case, it was stuck at 0 for smaller weights even before I weighed the beaker). 2601:646:8E01:7E0B:0:0:0:9ED6 (talk) 08:42, 21 March 2018 (UTC)

Does it have a zero button to re-zero it with no mass on the platform? Graeme Bartlett (talk) 09:58, 21 March 2018 (UTC)

Your description sounds like it was DOA. Even the best brands have this, so I wouldn't conclude from a single instance that the scale model is no good. If it sold as a new & working scale, the seller should set this right especially if they are a commercial seller. Nil Einne (talk) 10:40, 21 March 2018 (UTC)

What is "DOA"? 92.8.216.101 (talk) 13:41, 21 March 2018 (UTC)

The first sense at DOA—that is, dead on arrival. In the context of manufactured products, it means that the item was critically defective as-delivered. TenOfAllTrades(talk) 15:24, 21 March 2018 (UTC)

To get within 10 mg you want a jewelers' scale, which typically goes to 100g at the most. You can buy them in head shops among other places. You might be better off with a lab scale that has a draft shield; i.e., after putting your sample on the scale, you put a transparent box over the whole scale to prevent air currents in the room from disturbing the measurement. Digital scales measure weight using strain gauges which can be damaged if you put too much weight on them, so yes your scale might have gotten messed up if you overloaded it. Also, obviously, they measure force (F=M·g) rather than mass. If you really want to measure mass directly, you want a balance-type scale. I like typing "Ohaus" into craigslist search (sfbay.craigslist.org) just to see pictures of nice old ones, though I don't feel likely to buy one). 173.228.123.121 (talk) 19:56, 21 March 2018 (UTC)

Reflector telescope design

I'm looking for a reflector telescope design where the secondary mirror is offset out of the telescope tube. My motivation is (1) aperture control and (2) better bokeh. thanks! --Masatran — Preceding unsigned comment added by 117.251.229.98 (talk) 07:33, 21 March 2018 (UTC)

I think they're called off-axis reflectors. A curved spider in an on-axis reflector would get rid of the diffraction spikes at least (Maksutovs have a small secondary mirror but have a corrector plate that can't be 100.000% transparent). Sagittarian Milky Way (talk) 08:02, 21 March 2018 (UTC)

How long after last frost before lawns need mowing?

What temperature do lawns consider a frost? 32? 30? 28? 107.77.173.12 (talk) 17:56, 21 March 2018 (UTC)

The growth rate of the grass depends on too many factors to give a simple answer - temperatures, moisture levels, grass species, soil nutrient levels, sunlight levels. If it stays dull, and just above freezing, the grass will grow a lot more slowly than if the temperature shoots up very quickly and there is plenty of sunshine. Wymspen (talk) 18:18, 21 March 2018 (UTC)

Today, many people cut their grass too short. If you keep it no shorter than 2 inches (and I don't mean bowling greens but garden lawns). That too, will help prevent weeds colonizing (so avoid the need for lawn weed treatments). When in the spring, the grass grows to 3 inches, mow it on a day when there is no 'frost'. It is only when the ground is frozen that damage is done because grass grows from the base and any physical trauma will damage the leaf buds. --Aspro (talk) 19:11, 21 March 2018 (UTC)

Another thing to potentially consider 93.136.50.38 (talk) 00:29, 22 March 2018 (UTC)

Interesting question. I went ahead and asked on https://gardening.stackexchange.com/q/37656/13670 and was pointed to a UK news article differentiating between air frost and ground frost. The basic answer I got was that you can mow when the grass needs it (e.g. is >2inch tall) and it and the ground is not frozen. Generally the ground only freezes during extended day and night sub-freezing temperatures, similar to pipes freezing; it isn't immediate but takes extended cold temperatures, with shorter time required the colder it gets. A 32F night can result on frosty surfaces but the ground would not be necessarily be frozen. If the ground is not frozen and the grass itself doesn't have frost on it, the grass can handle a mowing, but if the ground is frozen or the grass itself has frost on it you're better off leaving the grass alone as the disturbance of cutting or even just bending the frosted plant material could injure it into the growing season. Cr0 (talk) 00:33, 22 March 2018 (UTC)

March 22

Did any cultures or parts of history not mentioned in the article have an international date line?

If you asked a say Medieval French or Classical Athenian scholar where the date changes is there any evidence giving a suggestion of what they might've said? Sagittarian Milky Way (talk) 01:14, 22 March 2018 (UTC)

This is a purely intuitive answer, but surely one has to undertake a circumnavigation, or at least cross the Pacific, before a date line becomes necessary? Alansplodge (talk) 09:29, 22 March 2018 (UTC)

Well, a thought experiment leading to the conclusion that there must be a date line is quite conceivable at any time after the Earth was known to be spherical. Double sharp (talk) 10:27, 22 March 2018 (UTC)

Well maybe, but the OP seems to be suggesting a culture which actually had a date line rather than who just thought it might be something that would one day be needed. Nil Einne (talk) 17:19, 22 March 2018 (UTC)

According to one researcher the earliest known texts mentioning gaining or losing a day by circumnavigating the Earth date to the 12th century. Whether someone thought of it earlier is hard to tell if they didn't pen it down. 85.76.72.88 (talk) 14:30, 22 March 2018 (UTC)

Thanks for the link! According to that site the first references to such a thought experiment demonstrating the need for a date line occur in the works of Abu'l-Fida and Nicole Oresme in the 14th century. The thought experiment in question is termed the circumnavigator's paradox, in which two people circumnavigate the globe in opposite directions while a third stays put at their starting point; when they meet each other again at that starting point, a different number of days have passed for each of them. Double sharp (talk) 14:59, 22 March 2018 (UTC)

The Medieval French scholar would probably have said "at the edge of Asia", since they didn't know about the Americas. (No, they didn't think the Earth was flat; this is a still-widespread myth in the English-speaking world.) For the Classical Athenian scholar, the idea was effectively meaningless to them. They had their calendar, and the barbarians had theirs, and the day starts for you when the Sun comes up. This only became something really necessary to consider with the advent of globe-spanning empires in the 1500s, and, the International Date Line article seems to indicate that Europe quickly settled on a line in the Pacific. Even then it only mattered for official record-keeping and similar things. Until the telegraph, you couldn't interact "live" with anyone whose solar time differed noticeably from yours, so why would the average person care what day it was on the other side of the globe? --47.146.60.177 (talk) 06:28, 23 March 2018 (UTC)

Oresme was a medieval French scholar, which would answer the first part of the question, except that the site previously linked does not show that he had a suggestion for where exactly the date line should be, only that he knew there had to be one: "one ought to assign a definite place where a change of the name of the day would be made". Double sharp (talk) 07:31, 23 March 2018 (UTC)

Yes, it is no coincidence that the closely allied concept of time zones is tied directly to the advent of railways long enough and quick enough to make it matter. Matt Deres (talk) 14:12, 23 March 2018 (UTC)

Of course, the exact Greenwich time around the world was known long before then Timeline of time measurement technology. Greenwich mean time has been around since 1675. 92.31.142.218 (talk) 14:52, 23 March 2018 (UTC)

Robert van Gent (who is one of our contributors) doesn't get it quite right [3]. The eleventh century view was that the date line was located six hours east of Jerusalem. Support for this theory comes from the fact of the start of the month being delayed should the conjunction occur at noon or later - at that moment the date will be the same everywhere. Also, with the sun being created at the beginning of the fourth day and the belief that it was on the Jerusalem meridian at that moment there is no other place for the date line to be. 92.31.142.218 (talk) 15:11, 23 March 2018 (UTC)

The question kind of assumes that the entire world uses the same calendar. The question would be, when did that happen? ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:04, 23 March 2018 (UTC)

The Gregorian Calendar was adopted by most Roman Catholic nations in 1582. Britain and its colonies, including what is now the United States, adopted it in 1752. Akld guy (talk) 22:22, 23 March 2018 (UTC)

When did China, et al, adopt the western calendar? ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:31, 23 March 2018 (UTC)

The whole world not using the same calendar didn't stop a date line from existing for Medieval Judaism. Also it doesn't have to be the same day on side X, Russian Alaska used the Julian calendar, and Canada used Gregorian and everyone using either calendar would agree that the date line is on their shared border. Sagittarian Milky Way (talk) 23:41, 23 March 2018 (UTC)

That would have nothing to do with what we call the International Date Line. ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:15, 24 March 2018 (UTC)

A pole to pole line does tend to be international but very well, let's call it the date line that was international to one culture but unheard of to entire continents. had at least a little currency in at least one culture. Sagittarian Milky Way (talk) 05:01, 24 March 2018 (UTC)

That changes the nature of the question, and you changed the section title accordingly. Maybe you should start over? ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:33, 24 March 2018 (UTC)

Like this? Sagittarian Milky Way (talk) 18:26, 24 March 2018 (UTC)

Contrary to Bugs, I reckon that the question assumes only that some set of people using one calendar had concerns around the world. The Chinese calendar isn't of concern to Spaniards communicating with South America and the Philippines. —Tamfang (talk) 04:48, 25 March 2018 (UTC)

The IDL would be of no importance in those cases. Each has dates and times relative to the Greenwich Meridian. ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:50, 26 March 2018 (UTC)

Did any cultures or parts of history not mentioned in International Date Line also have a stationary line where new dates are born?

Which had at least a little currency in at least one culture. Anyone who didn't comment due to interpreting international strictly is welcome to comment here. Sagittarian Milky Way (talk) 18:26, 24 March 2018 (UTC)

March 23

Gegenschein

The Submillimeter Array atop Mauna Kea in Hawaii

Is the bright spot in this image Gegenschein? I would like to add the image to the Wikipedia article for Gegenschein if so, but I want to be sure. Thanks! Steevven1 ^{(Talk) (Contribs) (Gallery)} 04:22, 23 March 2018 (UTC)

It looks too low to for it to not be twilight and ruin the picture, it's probably the zodiacal light. Sagittarian Milky Way (talk) 04:34, 23 March 2018 (UTC)

If I'm reading zodiacal light correctly, the first question to ask is whether the sun is immediately below the horizon in this image (in which case, it's zodiacal light) or is behind the photographer (in which case, it's gegenschein). Matt Deres (talk) 14:16, 23 March 2018 (UTC)

It can't be too immediately below the horizon, it has to be 40% of the way towards diagonally down or almost to be as dark as that photo. Sagittarian Milky Way (talk) 23:51, 23 March 2018 (UTC)

As an aside it is amusing that astronomers whinge on about light pollution but apparently their radio dishes are afraid of the dark and have to be illuminated at night. Greglocock (talk) 17:08, 23 March 2018 (UTC)

Joking apart, I'd guess that during the long exposure used for the sky, the photographer (or an assistant) walked up to each telescope in turn and illuminated it with a flash. [Which I now see is mostly confirmed by the photo's Summary data – duh!]

I concur that this is the Zodiacal light; one can clearly see its pyramidal shape, whereas the Gegenschein is discernably oval, and also less bright compared to the background sky, although the long exposures necessarily used for both can make this less obvious than to the naked eye. {The poster formerly known as 87.81.230.195} 2.218.14.51 (talk) 21:45, 23 March 2018 (UTC)

Thanks everyone! I'll add this image to the Zodiacal light article in a bit! Steevven1 ^{(Talk) (Contribs) (Gallery)} 00:41, 24 March 2018 (UTC)

Ultrasound repellent devices

Do these devices work? Could they work? Maybe insects are immune due to their lack of ears. But couldn't an ultrasound siren ward off at least cats and dogs? Dogs get normally scared by loud noises (like those of firecrackers), but would a 100-150 dB ultrasonic boom (not perceptible by humans) also scare them? Does ultrasound spread as well as sound in terms of range or intensity/distance? That is, would producing ultrasound through a tweeter be equivalent to producing normal sound through a loudspeaker? — Preceding unsigned comment added by Doroletho (talk • contribs) 23:08, 23 March 2018 (UTC)

I was going to direct you to our article, located at Electronic pest control, but it's pretty bad. Matt Deres (talk) 12:34, 24 March 2018 (UTC)

The article scratches the topic. But I don't mean concrete devices, or anything that you can find regularly in late night infomercials. As a matter of principle, could a burst of loud ultrasound scare some animals away? Specially dogs and cats, I imagine, are less likely to ignore noise. I suppose ultrasound is just noise for them. --Doroletho (talk) 13:03, 24 March 2018 (UTC)

It is the general consensus that animals rapidly grow used to such devices, limiting their effectiveness. Abductive (reasoning) 13:15, 24 March 2018 (UTC)

Such devices at a slightly lower frequency (15 to 18 KHz) have been used to deter teenagers from congregating in shop doorways. See The Mosquito and Acoustic harassment device. Dbfirs 17:34, 24 March 2018 (UTC)

@Dbfirs: what sort of unit is the KelvinHz? Klbrain (talk) 00:20, 25 March 2018 (UTC)

Thank you for drawing my attention to the typo. I meant kHz of course. Why can't SI units use consistent capitalisation? I was brought up on Imperial. Dbfirs 07:16, 25 March 2018 (UTC)

March 24

Tilting lens extension tube

Is a tilting lens extension tube available for any camera mount? I am interested in this since tilting lens adaptors do not provide autofocus. A tilting lens extension tube can trivially provide autofocus. I'm aware that distant focus would be impossible. --Masatran — Preceding unsigned comment added by 117.246.89.134 (talk) 00:26, 24 March 2018 (UTC)

It depends on your camera. If you have say a Nikon or a middle of the road Canon with standard screw threads on the lens mount then you have choices. Don't worry about focus. That just needs a bit of experimentation to become familiar with titling lenses and manual focus. Start by using a very small aperture (for maximum depth of field), then open up and use your eyes to check for focus on the main subject. --Aspro (talk) 01:38, 24 March 2018‎ (UTC)

Our article is at Tilt–shift photography. Graeme Bartlett (talk) 00:32, 25 March 2018 (UTC)

Janitorial questions.

When janitors see a sticker taped on the floor, I see sometimes they spray or pour a liquid solution 1st on it, then scrap the sticker off from the floor. What is that solution?

When janitors mop floors, with the flooring or Pinesol solution, do they add a little bleach to it? I was a janitor at a residential building before, and I was taught to add a teaspoon of bleach to the bucket. But at a retail clothes store, they don't use bleach, because they think it will change the color of the floor or damage it (or whatever reason). I don't believe bleach is harmful to floor tiles and such. Is there certain flooring material where you shoudnd't use bleach? Thanks. 67.175.224.138 (talk) 18:55, 24 March 2018 (UTC).

The solution to get rid of the sticker probably varies. Distilled white vinegar does wonders for that sort of thing.

I have to wonder if that retail store was using a cleaner that reacts with bleach (it's possible to make mustard gas with bleach and other certain common cleaners). As a general rule, cleaners that are safe to mix are an exception to the rule "never mix cleaners."

Then again, my experience at Walmart leads me to believe that it's entirely possible that "bleach harms the floor" might not have been the original reason. Not that they were lying to you or anything, but the person who told you that may have been told that by someone who forgot why they actually don't use bleach, and/or the decision to not use bleach was only half-informed and didn't give a very clear reason to begin with. -- But that's just from my experience at a poorly managed Walmart in a bad neighborhood, I understand that some retail places aren't proof that Satan is real and active in the world. Ian.thomson (talk) 19:12, 24 March 2018 (UTC)

I agree. People are incredibly stupid and will mix bleach and ammonia, so any lie you can tell them to prevent them using bleach will persist, since people that know better don't want the stupid to die. Abductive (reasoning) 19:24, 24 March 2018 (UTC)

• There's Goo Gone and Goof Off, and even Fabuloso contains alkyl alcohol ethoxylates. Abductive (reasoning) 19:22, 24 March 2018 (UTC)

FWIW, I have found that to remove stickers and their residue from solid surfaces and – most particularly in my case – (glossy) paperback book covers, lighter fluid is usually effective and leaves no stain or colour bleeding, though one should always test beforehand. {The poster formerly known as 87.81.230.195} 2.218.14.51 (talk) 23:57, 24 March 2018 (UTC)

Other sticker removing liquids are orange oil or eucalyptus oil. The first may stain, but both smell good. Graeme Bartlett (talk) 00:30, 25 March 2018 (UTC)

I have seen packaged floor tiles that include manufacturer's instructions saying "do not use bleach" on the tiles. Bus stop (talk) 00:47, 25 March 2018 (UTC)

Linoleum contains linseed oil, so I was thinking bleach might do lipid peroxidation, more or less. I looked this up and found sites saying don't use it. [4][5] Second link actually blames the pH. Clorox claims you can use it, if diluted. [6] Honestly I have no idea. To add to the fun, the pigments in flooring might be anything, and who knows if they resist bleach or not? I see why caution rules the day since it must be hard for a janitor to blame a whitened or cracked floor on sorority drinking games. ;) Wnt (talk) 01:42, 26 March 2018 (UTC)

Bleach would also likely damage the clothes, so prohibiting its use in a clothing store would avoid accidents (either spill/spash while cleaning, or product falling in residue afterwards). DMacks (talk) 06:41, 26 March 2018 (UTC)

March 25

What model of Atmos clock is this?

It's a Jaeger-LeCoultre Atmos clock, but what model?

I am trying to figure out what the model number for this Atmos clock is. --Guy Macon (talk) 05:45, 25 March 2018 (UTC)

(...Sound of Crickets...) --Guy Macon (talk) 02:26, 26 March 2018 (UTC)

"Choip!" (Brooklyn cricket) ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:43, 26 March 2018 (UTC)

It's an Atmos Classique Transparente Phases de Lune, part number starts with 580, perhaps? Abductive (reasoning) 04:14, 26 March 2018 (UTC)

bug identification

I've seen quite a few specimens of this kind of insect over the course of the past month in Israel. They fly rather erratically (bouncing around) and are easy to swat when they've landed (unlike, for example, houseflies, which easily dart away). They are, I'd say, perhaps around five centimeters in diameter including the bent legs. What are they, please?—msh210℠ 10:30, 25 March 2018 (UTC)

Almost certainly a Crane fly. Rojomoke (talk) 11:14, 25 March 2018 (UTC)

Many thanks.—msh210℠ 12:18, 25 March 2018 (UTC)

Known to English children as "Daddy longlegs" (confusingly, a name also given to Opiliones or "harvestmen" who are even more well-endowed in the leg department). Alansplodge (talk) 16:23, 25 March 2018 (UTC)

And some children here in the states too. Then there's some Americans who use "daddy long legs" for the Pholcidae cellar spiders. So while best bet is to use the Latin, harvestmen/crane fly/cellar spider are common names that avoid the problems with daddy long legs. SemanticMantis (talk) 15:45, 27 March 2018 (UTC)

DST and sun

During the daylight saving time, when the clocks are advanced further (one hour forward, in particular), does it mean that the sun reaches zenith at 13:00 local time instead of theoretical 12:00, as shown by sundial? Thanks. 212.180.235.46 (talk) 15:25, 25 March 2018 (UTC)

No. Full width time zones have to be at least 30 minutes in error on at least one edge (often more since states, counties and countries don't end at exactly the right longitude and people like to shift them west for fake DST). And a modern clock has a very consistent pace compared to a sundial, it's only an average of what the sundial says. Sundials and local solar time can be up to 16 minutes wrong (more in some of the far future and past) which currently occurs in November, the same month DST ends in North America. The band where noon is 13:00 to the second is about 300 meters wide at European latitudes and could be kilometers away the next day. Sagittarian Milky Way (talk) 16:57, 25 March 2018 (UTC)

Yes, this is true that when you advance clocks by one hour the true solar noon happens later by one hour. Ruslik_Zero 20:00, 25 March 2018 (UTC)

That's a most unfortunate way of putting it. The solar noon doesn't change, but the time we attribute to it advances because of the clock being advanced. This doesn't happen with a normal sundial, though it would be possible to swivel it around a central column to advance or retard it. Akld guy (talk) 22:30, 25 March 2018 (UTC)

Right, and as noted above, solar noon is often not at noon local time in the first place. For an extreme case, Time in China, the People's Republic of China uses only one time zone "officially", so in its west the official clock time is hours ahead of solar time. --47.146.60.177 (talk) 20:17, 25 March 2018 (UTC)

Further to earlier answers, the fact that the Earth's orbit around the Sun is not circular, but elliptical, means that the Earth's orbital speed varies over the year, resulting in actual or apparent noon (when the Sun actually appears on the meridian – i.e. due north or south depending on the hemisphere one is in) often being earlier or later that what is indicated by unvarying-rate clocks, which show the averaged mean solar time, by up to a quarter of an hour. The mathematical description of this is called the Equation of time, which article should explain this in detail. {The poster formerly known as 87.81.230.195} 2.218.14.51 (talk) 00:47, 26 March 2018 (UTC)

There's also detail at solar time. This article is unfortunately permanently locked to keep in "fake news" (that's why some of our administrators are here). According to the current (fake) version "Long or short days occur in succession, so the difference builds up until mean time is ahead of apparent time by about 14 minutes near February 6 and behind apparent time by about 16 minutes near November 3. The equation of time is this difference, which is cyclical and does not accumulate from year to year." In reality, instead of building smoothly the difference goes into reverse between 14 May and 26 July. This was explained in the correct (locked out version) as follows:

Because many of these long or short days occur in succession the difference builds up. This difference, the equation of time, is at a maximum absolute value at the point where the length of a day again reaches its mean value - sundial ahead of the clock 16m 33s on 3 November with a smaller maximum on 14 May, sundial behind the clock 14m 06s on 12 February with a smaller minimum on 26 July. The equation of time is this difference, which is cyclical and does not accumulate from year to year.

Similar "fake news" was locked into "Equation of time" at the same time. The current (fake) version reads:

But the orbit of the Earth is an ellipse not centered on the Sun, and its speed varies between 30.287 and 29.291 km/s, according to Kepler's laws of planetary motion, and its angular speed also varies, and thus the Sun appears to move faster (relative to the background stars) at perihelion (currently around 3 January) and slower at aphelion a half year later.

At these extreme points this effect varies the apparent solar day by 7.9 s/day from its mean. Consequently, the smaller daily differences on other days in speed are cumulative until these points, reflecting how the planet accelerates and decelerates compared to the mean.

The correct (locked out) version read:

But the orbit of the Earth is an ellipse not centred on the Sun, and its speed varies between 30.287 and 29.291 km/s, according to Kepler's laws of planetary motion, and its angular speed also varies, and thus the Sun appears to move faster (relative to the background stars) at perihelion (currently around 3 January) and slower at aphelion a half year later. At these extreme points this effect causes the apparent solar day to vary by 7.9 s/day from its mean. The mean velocity is reached between perihelion and aphelion - while the velocity is in excess of the mean (early October to early April) the component due to eccentricity becomes more positive and while the velocity is below the mean (early April to early October) this component becomes more negative.

YouTube has just begun adding extracts from Wikipedia to biased videos to counteract the extremism. We want to develop this relationship. The administrators who are promoting the "fake news" are shooting the Project in the foot. 2A02:C7F:BE3D:8000:C5C1:6C71:664A:D26 (talk) 12:31, 26 March 2018 (UTC)

References

I used to live in Leytonstone where the Greenwich Meridian passed across the end of my road. So in that case, the answer would be "yes", the sun does reach its zenith at 13:00 local time instead of theoretical 12:00. Alansplodge (talk) 15:07, 26 March 2018 (UTC)

Only when the equation of time was 0. Noon was as early as 11:44 every early November when it was extreme. The abstract mean sun that clocks use was always exactly 13:00 or 12:00, though. Okay, okay and then you have British Standard Time usually being 0 to 0.5 or 0.6 seconds from the real mean sun cause day inflation (24 hours 0.002 seconds), earthquakes, glaciers melting and stuff but leap units are only seconds predicted long in advance but who cares about that. Sagittarian Milky Way (talk) 21:44, 26 March 2018 (UTC)

March 26

Transformers (not robots)

About how heavy are typical transformers of the sort which are placed on power poles? Would it be possible to squeeze one of those into a Mooney Bravo? 2601:646:8E01:7E0B:E5E2:F910:E2B4:1B46 (talk) 04:45, 26 March 2018 (UTC)

If you could squeeze hard enough, you could transform it into any shape you want. ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:01, 26 March 2018 (UTC)

That aircraft can only carry 454 kg. Power pole mounted transformers can have a range of sizes. So what sort of capacity do you want? When I look at a 200kVA model, I don't think you will get it in the passenger compartment. Even if there is a freight compartment, it will be much smaller than the passenger space, and you would not get it in there. The weight of the Federal Pacific FPE-Reliance-225KVA-480-220Y-127V-3PH-Dry-Type-Transformer-Used-E-OK is 1100 pounds; a 100 kVA unit may be 600 kg, both still too heavy. Graeme Bartlett (talk) 06:07, 26 March 2018 (UTC)

That 3PH is likely a set of three single-phase transformers in a metal box for mounting in dry locations. A pole-mount is usually separate single-phase units wired together. Consider instead 100 kVA Utility Pole Mount Transformer - 14400/24940Y Wye-N Primary - 240/480V Secondary - Copper, which lists a weight of 1220 pounds. It takes 477 pounds of mineral oil, and I'm not sure if that is included in the 1220-lb weight. DMacks (talk) 06:37, 26 March 2018 (UTC)

• Heavy. They're stationary and located in remote places, so they're designed for reliability, not light weight. They're based on a heavy iron core and on oil cooling. If you wanted a lightweight design, could afford to sacrifice some efficiency for weight saving, and had access to a stream of cooling air, then you could do a lot better. You might even switch to a higher line frequency, which would allow a more efficient core material, like a ferrite. Andy Dingley (talk) 10:03, 26 March 2018 (UTC)

Great -- and the useful weight includes the fuel (all 534 lbs. of it) as well as the payload. So then tell me, what other equipment could be needed at a shoe factory which is light enough for the Mooney to carry? (This is for a fictional scenario -- I'm doing an IFR flight in FSX from Boeing Field to Scappoose Industrial Airpark, and I want something I could use as a payload -- the story being that something broke at the factory and they need it replaced right away, and I'm the only pilot who can deliver the spare parts on such short notice.) 2601:646:8E01:7E0B:E5E2:F910:E2B4:1B46 (talk) 12:42, 26 March 2018 (UTC)

Well traditionally, it's a Shoe Factory Repairman.

I used to work for a guy who flew a helicopter, lived a long way away, and we had machinery in a nearby car factory built on an old airfield. He'd often fly up and we'd both visit this factory by helicopter, just so that he could keep up his flying hours and also treat it as a business expense. Andy Dingley (talk) 13:40, 26 March 2018 (UTC)

What era is this supposed to be? eBay lists lots of relevant equipment of different vintages and sizes, and many of the larger ones obviously have lots of small but critical parts that could need replacing too. DMacks (talk) 16:19, 26 March 2018 (UTC)

It's supposed to be early 21st century (it's part of an ongoing story which I'm telling with a series of YouTube gaming videos, and there will be a time warp which sends the main character 100 years back in time, but at this point the time warp hasn't happened yet.) 2601:646:8E01:7E0B:E5E2:F910:E2B4:1B46 (talk) 08:33, 27 March 2018 (UTC)

When trying to put industrial equipment in a small airplane (or a large one!), you must concern yourself not only with weight, but also with balance. In fact, the February issue of FAA Safety BLAST had a great article on this exact topic: Minding Weight, Maintaining Balance from the NTSB. Here's the official Weight and Balance textbook, and here's an unofficial online calculator for the Mooney M20J: "This calculator is presented for educational purposes only." Remember: you need a correct calculation with exact data not only for every make and model, but for each tail number, whose exact empty weight and balance may vary from the standard aircraft.

As a general rule of thumb, putting two hundred pounds in the baggage compartment of a small single-engine aircraft does not work, even if it weighs less than the aircraft's "total useful load." Overloading the baggage compartment moves the center of gravity aft, possibly beyond the aircraft's safe operating envelope. When that occurs, the aircraft is difficult to fly, and may be aerodynamically unstable. In the worst cases, the aircraft is completely uncontrollable - e.g. no amount of elevator trim can keep the aircraft in level flight; nothing you push or pull in the cockpit will make any difference.

And don't forget to account for fuel weight and balance - for all phases of the flight - because fuel gets used up in the air! These little piston engines can carry a lot less actual cargo than you might think!

The pilot's job begins long before they take their seat in the cockpit!

Nimur (talk) 15:36, 26 March 2018 (UTC)

Re: "So then tell me, what other equipment could be needed at a shoe factory which is light enough for the Mooney to carry?", it just so happens that I designed a shoe factory many years ago (not the building, but pretty much everything inside it other than the workers). Your best bet for critical part that a small aircraft could carry is an electric motor. They range in size from the size of your fist to too heavy for the plane, so you can write a "just barely able to make it" scenario and have it be believable. If you want to get fancy, have the plane carry a servomotor and associated control unit. Also, it isn't plausible that no pole mounted transformers are available; every building has one.

Consider also that, presuming your fictional work might have non-North American readers, such pole-mounted transformers would likely be unfamiliar to them. For instance, as an aged Brit who has worked for facilities maintenance and installation companies in the UK, I've never seen or heard of them before now. {The poster formerly known as 87.81.230.195} 2.218.14.51 (talk) 23:40, 26 March 2018 (UTC)

Thanks! I don't know all the details of a shoe factory (I'm a chemist by trade, not a shoemaker or a mechanical engineer), but I do know the kinds of machines they use in general, and I know that lots of stuff uses electric motors -- so just one last question, which machines at such a factory are the most critical (i.e. if they break down, the whole plant could go offline -- which would give extra urgency to having it replaced right away, even if it means paying extra AND breaking normal procedure)? 2601:646:8E01:7E0B:E5E2:F910:E2B4:1B46 (talk) 08:33, 27 March 2018 (UTC)

Aside: This is not on topic but. During the 2nd World War the RAF often had to bomb U boats at night. Radar could detect them from a distance, but the boats immediately did an emergency dive on the aircraft’s approach. The only way that the aircraft could then home in on the U-boat was to illuminate the whole target area with light for visual aiming. A generator to provide that amount of illumination was too heavy, but since they only need brief intensive illumination they use lead acid batteries. As Michael Caine might have said “ not a lot of people know that”. Aspro (talk) 21:08, 27 March 2018 (UTC)

Non-cylindrical aerosol can

Would it be too bothersome, expensive or unsafe to design an aerosol can (for deodorant, for example) that does not have a cylindrical form? It would obviously not have any practical advantage over a cylinder. But in product design many things are the way they are just to 'look cool'. --Hofhof (talk) 12:21, 26 March 2018 (UTC)

An aerosol can is basically a pressure vessel, Pressure vessel#Shape of a pressure vessel has a discussion of the issues involved, and even has an aerosol can as an example. --Jayron32 12:35, 26 March 2018 (UTC)

A spherical can would have advantages. Looie496 (talk) 13:36, 26 March 2018 (UTC)

And disadvantages. Please see the above link, which mentions both. --Jayron32 13:43, 26 March 2018 (UTC)

• Very few are simple cylinders. Even hairspray has domed ends, one concave, one convex.

The pressures are low. It's not hard to make them of any rough shape, one-off tooling costs permitting. What's more of a design problem is to avoid unsupported corners. A flat-sided oval tank may be pressurised, even though it has flat sides, but sharp corners are avoided because they would represent the highest stresses and would be the first part to require reinforcement. It's common to have sharp corners where the ends join on, but these are only a single edge, not multiple edges joining in a corner, and they also have a stiffened rim as reinforcement. Andy Dingley (talk) 14:02, 26 March 2018 (UTC)

I found Shaped Aerosol Cans, but they are still fundamentally cylindrical and I imagine more expensive than the plain ones. Alansplodge (talk) 15:01, 26 March 2018 (UTC)

As a digression, what's the best name for a shape like this which is an "un-prism"? These shapes seem to maintain radial symmetry (for structural reasons about the recognised benefits of a circular pressure vessel), but vary the diameter along their axis. Andy Dingley (talk) 19:59, 26 March 2018 (UTC)

A solid of revolution is circular symmetry#Three dimensions. I don't understand the "unprism" terminology idea. DMacks (talk) 20:51, 26 March 2018 (UTC)

Thanks, that's another tickbox for the dementia diagnosis. My "un-prism" is that these are asymmetric in just the way that prisms are symmetric. Andy Dingley (talk) 21:22, 26 March 2018 (UTC)

No worries:) Thinking more, some of them could be more an antiprism, which has radial symmetry with specific steps around rather than a smooth rotation. DMacks (talk) 21:42, 26 March 2018 (UTC)

• Lynx (known as Axe in the US) has cans with hard corners like this. I don't think this shape has a technical name, but it's a lofted shape with a circular cross-section at one end, and a slightly rounded square at the other end. I think being flat makes it a bit easier to hold (so you spray it where you want to spray it, rather than accidentally pointing the nozzle in the wrong direction). Smurrayinchester 09:26, 27 March 2018 (UTC)